It makes me happy that you might want to pursue teaching as a profession. As an English teacher myself, I always appreciate the students who actually enjoy reading Macbeth as opposed to feeling like it is a chore they must do.
One thing I have learned as I have taught high school (I teach seniors) is that from your junior year to your first year of college you may completely change what you want to do with your life...and that is OK. You don't have to have all the answers by the end of your junior year. Trust me on this. However it is good that you do have an idea and some direction.
I would suggest you read some stuff out there on teaching and education. i'm sure if you look through the archives of these forums you will find some titles. i'm currently reading a book by Alfie Kohn called The Schools our Children Deserve. It is really enlightening....rather academic and heady but it will give you some insight on what "good" education should be.
I don't know what the requirements are for becoming a teacher in your state. I would ask one of your current teachers on that. That will dictate what area you should studey in college....if you should major in education as well as english. Very rarely (if ever) do you enter a school to //just// teach creative writing. Usually creative writing classes are given to current English teachers as an elective class to teach. This may be different in your area, but in FL this is the norm.
Hope this helps some,